The inventor has already carded out attempts with blast-air cooling equipment, which has a heat exchanger, through which a cooling liquid flows. The equipment also has an air inlet, an air outlet and a blower, which drives air from the air inlet to the air outlet through the heat exchanger and from the air outlet side onto the surface of a rotating, cylindrical printing plate. With this air, the surface of the cylindrical printing plate may be maintained at a temperature between 24.degree. and 27.degree. C.
It is an object of the invention to drastically reduce the energy required to operate the blast-air cooling equipment. A further object of the invention consists of integrating the blast-air cooling equipment into a printing system for keeping the printing plates at a moderate temperature so that the cooling equipment may be incorporated into a variety of printing systems. The cooling equipment could be, for example, blast-air cooling equipment (waterless offset printing); inkers, so-called ink rollers, through which a cooling liquid flows (waterless offset printing); or with a damping liquid, which is applied on the surface of the printing plate (damping mixture offset printing). For each of these three different modes of operation, the energy required for the operation is reduced. Another object of the invention is constructing a system for maintaining a moderate temperature such that it can be produced inexpensively. It is furthermore an object of the invention to construct the system for keeping the printing plates at a moderate temperature so that it can be converted in a short time and without extensive structural measures from one mode of operation to another mode of operation. This mode switching preferably shall be possible simply by switching valves, without having to dismantle or modify machine pans.
This objective is accomplished pursuant to the invention by the distinguishing features of claim 1.